What’s this for?

[chriscraw]

On my 1991 350LE, I recently replaced the by-pass valves under the rear buffet seat (caused by poor winterizing.
I noticed this valve attached to the water heater and seem to recall that Airstream fitted plumbing to route engine coolant through the water heater so as to provide for hot water for a refreshing shower upon arrival at the overnight stop. Could this be the bypass valve for this remarkable innovation?
It is currently in the closed position. Water heater works fine.
Any thoughts

[Isuzusweet]

It certainly does look like it Chris, but I am surprised at the choice of plumbing pipe they used; mine is copper into rubber coolant hose.

The best way to check would be to take your coach out for a run with hot water tank off and check heat in pipes once coach coolant is up to temp. Heat in pipes will be a dead giveaway.

Cheers
Sidekick Tony

[mehes]

I believe this valve bypasses your water heater. One of the engine coolant heat assist lines can be seen in the shadows in the lower left. Black rubber hose with stainless steel screw clamps. There usually are no valves associated with these. Simply in, out any time the engine is running.

[chriscraw]

Tony and "mehes"..thanks for your respective confirmations. Now that you've confirmed that the valve is related to the engine/water heater process, I can happily move the valve to open as needed.
I was however surprised to read your comment Tony that your lines were "copper" whereas mine was Pex. I would have thought that the "LE" designation would have entitled me to copper?
On a similar but related note. The burst valve water damage caused by poor winterizing also saturated the "cardboard" covering the water heater as well as the insulation. Any thoughts on pulling it all off and replacing with more modern insulation?

[Boom Sounds]

I have the same problem. Precisely the same set up with that valve. One of the small drain pipes has cracked due to pot winterising plus my ‘cardboard wrapper’ has water staining. I look forward to seeing your fix

[mehes]

I guess I wasn't too clear in my previous post. This valve is not for the engine coolant. This valve diverts the cold water inlet to the hot water outlet for bypass condition. In its other position it will supply cold water to the water heater for normal operation. The grey plastic lines are your water lines. The black rubber hoses are the engine coolant lines.

[AlinCal]

FYI The piping is PB or Polybutyene and not pex pipe.

[HowieE]

What you have pictured is the bypass valve for winterizing. There is NO WAY engine coolant could be circulated through the hot water heater.

That said I would be interested in a better shot of the black piping shown going under the heater. They could have a plate heater mounted to the bottom of the water heater and use that to transfer heat to the water heater.

Can you post a closer look at those pipes.

[chriscraw]

Originally Posted by Boom Sounds

I have the same problem. Precisely the same set up with that valve. One of the small drain pipes has cracked due to pot winterising plus my ‘cardboard wrapper’ has water staining. I look forward to seeing your fix

nick..no replies as yet..will keep you in the loop.
Seems I really got onto the wrong track with the valve question..see below

[chriscraw]

Originally Posted by AlinCal

FYI The piping is PB or Polybutyene and not pex pipe.

Sorry for the faux par but my excuse is that I've replaced old PB with new PEX...got confused..BTW..1/2 inch Sharkbite fittings will work on the PB

[chriscraw]

Originally Posted by HowieE

What you have pictured is the bypass valve for winterizing. There is NO WAY engine coolant could be circulated through the hot water heater.

That said I would be interested in a better shot of the black piping shown going under the heater. They could have a plate heater mounted to the bottom of the water heater and use that to transfer heat to the water heater.

Can you post a closer look at those pipes.

Thanks, Howie..of course, you are correct but how should the by-pass valve be used. Right now, it's vertical as per above pic....when would it be "in-line"?
As for the heater plate...if I ever can get underneath the water heater. This explains the black water lines seen in the pic.

[chriscraw]

Originally Posted by mehes

I guess I wasn't too clear in my previous post. This valve is not for the engine coolant. This valve diverts the cold water inlet to the hot water outlet for bypass condition. In its other position it will supply cold water to the water heater for normal operation. The grey plastic lines are your water lines. The black rubber hoses are the engine coolant lines.

Thanks for the clarification..makes more sense. Right now as seen in the pic, the valve lever is in the vertical position...is this the normal pistion to supply cold water to the water heater?
Then, in the horizontal position, this would divert cold water inlet to the hot water outlet.Why..perhaps for winterizing?
I remain confused!
Chris

[mehes]

The valve appears to be in the bypass (winterize) position. Normally to winterize, you would move the valve to the position shown, drain the water heater tank by the external drain plug, and ether drain or blow out the remaining water lines with compressed air. Then an RV antifreeze can be pumped into the water lines for winter protection. The diverted valve saves you from filling the six or so gallons of the water heater tank. In the spring the antifreeze is either drained first or simply flushed out with fresh water, and the diverter valve returned to the normal position. In your case horizontal most likely. Only use RV antifreeze intended for the purpose, automotive antifreeze can be hazardous to your health. Hope this helps you some.

[chriscraw]

Note to Mehes and Tony...Thanks for your succinct explanation of how this valve should be positioned. I now understand its function and operation. Much appreciated
Note to Nick...
There has been no response to my question regarding how to remove and replace the cardboard cover and insulation covering the water heater. After having a closer look and with some success drying-out cover and realizing that to do the job properly will mean disconnecting multiple lines, I've decided to "suck-it-up" and leave well alone for the time being. I'm also anxious to complete other tasks before heading the unit up to Santa Fe on April 10.
Let me know if you read of any less intrusive solutions.